Abstract:Abstract: A semi-analytical method of dynamic load identification in time domain is proposed based on modal space transformation, least square fitting and modal superposition. At first, the problem of dynamic load identification is converted to the identification of modal coordinate functions by modal space transformation; then using the structural characteristic parameters and dynamic responses of some given degrees of freedom as the input of load identification, the least square fitting is employed to obtain the fitting functions of modal coordinates; finally, the dynamic loads in time domain are identified by utilising the principle of modal superposition and the governing equations of structural dynamics. The processes of load identification are carried out by taking the acceleration responses derived from simulation and experiment respectively as the inputs. The comparisons between the identified loads and the real ones show that, this method can meet the requirements of identifying the values of dynamic loads and their locations.